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United States Patent |
5,255,702
|
Journee
,   et al.
|
October 26, 1993
|
Venting system for a fuel tank
Abstract
A venting system for a motor vehicle fuel tank comprises a fuel tank having
a filling pipe, an overflow duct, a gas vent duct, a safety valve; fresh
air duct for removal of excess fuel vapour from the fuel tank through the
fresh air duct. A scavenging duct and an auxiliary valve for overcoming
failure of the scavenging duct and/or of the safety valve, in order to
ensure that the fuel tank is vented through the fresh air duct are also
provided.
Inventors:
|
Journee; Maurice (Reilly, FR);
Hyernard; Pierre-Andre (Paris, FR);
Romanek; Christian (Noailles, FR)
|
Assignee:
|
Paul Journee S.A. (Colombes Cedex, FR)
|
Appl. No.:
|
702373 |
Filed:
|
May 20, 1991 |
Foreign Application Priority Data
Current U.S. Class: |
137/202; 137/588; 220/746 |
Intern'l Class: |
F16K 024/00 |
Field of Search: |
137/43,202,587,588
220/746,749
|
References Cited
U.S. Patent Documents
4000828 | Jan., 1977 | Crute | 137/43.
|
4742809 | May., 1988 | Ito et al.
| |
4893643 | Jan., 1990 | Gifford | 137/588.
|
4974645 | Dec., 1990 | Johnson | 137/587.
|
5004002 | Apr., 1991 | Kobayashi | 137/43.
|
Foreign Patent Documents |
0254631 | Jan., 1988 | EP.
| |
0336788 | Oct., 1989 | EP.
| |
3605708 | Oct., 1986 | DE.
| |
2221938 | Oct., 1974 | FR.
| |
2593752 | Aug., 1987 | FR.
| |
2606856 | May., 1988 | FR.
| |
Primary Examiner: Nilson; Robert G.
Attorney, Agent or Firm: Dennison, Meserole, Pollack & Scheiner
Claims
What is claimed is:
1. A system for filling the tank of a motor vehicle with fuel and for
venting fuel vapor comprising:
a filling pipe with a neck portion connected to said tank and an open end,
means for selectively closing and sealing the open end,
duct means and valve means joined to said neck portion, said duct means
capable to discharge excess fuel to atmosphere and cooperating with said
valve means to define a passage for continuously venting said tank while
said filling pipe end is closed,
said valve means including a safety valve portion which is in the open
position during normal operation for interconnecting the tank through said
duct means to atmosphere and an auxiliary valve portion responsive to
failure of said safety valve portion, for ensuring uninterrupted tank
venting in the event said safety valve portion is in the closed position,
wherein said duct means includes a gas vent duct,
a fuel having an inlet and an outlet, said inlet communicating with the
tank and the filling pipe neck portion and said outlet communicating with
said fresh air duct,
said safety valve portion responding to fuel surging into the filling pipe
by changing to the closed position so as to prevent escape of fuel while
the vehicle is operated and said auxiliary valve portion allowing the
correction of pressure differences between tank interior and outside air,
said auxiliary valve portion continuing the correction during failure of
the safety valve portion to return to the open position.
Description
FIELD OF THE INVENTION
This invention relates to a venting system for a fuel tank, in particular a
fuel tank for a motor vehicle.
BACKGROUND OF THE INVENTION
The specification of the French published patent application FR 2 593 752A
discloses a system which comprises a fuel tank having a filling pipe, a
first conduit referred to as an overflow duct, a second conduit referred
to as a gas vent duct, and a third conduit referred to as a fresh air
duct. The filling pipe terminates in an orifice with a fuel cap for
covering the orifice so as to close the pipe when not in use for filling
purposes.
The overflow duct extends from the interior of the fuel tank, and
terminates at the level of the upper part of the filling pipe, and its
purpose is to evacuate any excess fuel from the fuel tank towards the
filling pipe. The gas vent duct extends from the top of the fuel tank, and
again terminates at the level of the upper part of the filling, pipe. The
gas vent duct is required in order to permit all the necessary variations
to take place in the volume of residual air present in the upper part of
the tank; it also serves to accommodate any possible surges of fuel. The
gas vent duct is able to be in communication with the filling pipe after
the filling orifice has been closed with the fuel cap.
The fresh air duct is the external venting means whereby any build up of
fuel vapour in the system can be allowed to escape to the atmosphere
outside the vehicle. This may typically occur for example during
refuelling. By the same token there may be an excess of pressure
(over-pressure) in the fuel tank or in the system, due to increase in the
volume of fuel in the tank and the consequent presence of fuel vapours and
reduction in the volume within the tank available for accommodation of air
in the latter. Thus the purpose of the fresh air duct is either to vent
the tank so as to allow vapours and over-pressures of air to escape, or to
correct any under-pressure resulting from consumption of the fuel while
the vehicle is running, by admitting free air from outside into the tank
through the fresh air duct itself.
The specification of European published patent application No. EP 0 336
788A discloses the provision of a safety valve between the gas vent duct
and the fresh air vent, with a view to preventing any fuel from escaping
from the fuel tank. Such escape of fuel may be caused by jolting in the
vehicle or by the positioning of the vehicle on a steep slope (for example
when stationary); or even by the vehicle being turned upside down in a
accident.
This safety valve comprises a valve member which is adapted to close an
outlet, by means of either a float which is actuated by the fuel itself,
or a biassing means which is responsive to the inclination of the vehicle
or to accelerations or decelerations of the vehicle. Such a biassing means
may for example comprise either a ball which is mounted between inclined
ramps, or a calibrated spring.
As described in the above mentioned European patent specification, the
safety valve may be used in association with a fourth duct, referred to as
a scavenging (or de-pollution) duct. Such a scavenging duct is described
more fully in the specification of U.S. Pat. No. 4,742,809, and serves to
separate the air from the fuel vapours by condensing the latter so that
they can then return in liquid form to the fuel tank: the scavenging duct
is however so arranged that clean air can still escape to the outside.
The present Applicant has found however that these various known
arrangements have a number of drawbacks. In particular, in the situation
in which the valve member of the safety valve is immobilised in a position
in which it obstructs or closes the outlet orifice of the safety valve,
any excess or deficiency in pressure that may arise is unable to be
corrected, and any fuel vapour that may be present in the interior of the
fuel tank is unable to be evacuated, by passage of air into the system
through the said outlet orifice, or by passage of air and/or vapour from
the interior to the outside via the same orifice, as the case may be.
In addition, if the scavenging duct is obstructed by some impurity, the
fuel vapours are unable to be conveyed to the scavenging system, and are
therefore liable to set up an excess of pressure in the fuel tank which is
then unable to be corrected.
OBJECTS OF THE INVENTION
An object of the present invention is to overcome the disadvantages
mentioned above, by providing a venting system for a fuel tank which is of
very simple design and which avoids the possible effects of any
malfunction.
SUMMARY OF THE INVENTION
According to the present invention, a venting system for a fuel tank,
especially for motor vehicles, comprises a filling pipe, an overflow duct,
a gas vent duct, a fresh air duct, a safety valve, and (optionally) a
scavenging duct, and an auxiliary valve is provided for overcoming failure
of the scavenging duct and/or of the safety valve., in order to ensure
that the fuel tank is vented through the fresh air duct.
The provision of the auxiliary valve in the system according to the
invention enables fresh air to be passed into the fuel tank whenever
required, and thus ensures that any over-pressures or under-pressures in
the fuel tank can be corrected.
The other features and advantages of the invention will appear more clearly
from the following description, which is given by way of example only and
with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows diagrammatically the filling pipe and its various ducts,
together with the safety valve.
FIG. 2 also shows a filling pipe with its various ducts, apart from the
scavenging duct.
FIG. 3 is a view in cross section, showing part of the filling pipe in
relation to FIG. 1, and having a venting device in accordance with the
invention.
FIG. 4 is a top plan view on FIG. 3.
FIG. 5 is a view in cross section showing part of the filling pipe with a
venting device in a second embodiment of the invention, being a first
variant on that shown in FIG. 3.
FIG. 6 is a plan view on FIG. 5.
FIG. 7 is a view in cross section showing part of the filling pipe with a
venting device in a third embodiment of the invention, being a second
variant on the version shown in FIG. 3.
FIG. 8 is a top plan view on FIG. 7.
FIG. 9 is a view in cross section showing part of the filling pipe with a
venting device in a fourth embodiment of the invention, being a third
variant on the version shown in FIG. 3.
FIG. 10 is a view identical with that of FIG. 9, and shows the venting
device in a working state.
FIG. 11 is a view in cross section showing part of the filling pipe with a
venting device in a fifth embodiment of the invention, being a fourth
variant of the embodiment shown in FIG. 3.
FIG. 12 is a view in cross section showing part of the filling pipe with a
venting device in a sixth embodiment of the invention, being a fifth
variant on the embodiment shown in FIG. 3.
FIG. 13 is a view in cross section, taken on the line 13--13 in FIG. 12.
FIGS. 14 and 15 are views in cross section showing part of the filling pipe
in relation to FIG. 2, having a venting device in accordance with the
invention.
FIGS. 16 and 17 are views in cross section showing part of the filling pipe
with a venting device in a further embodiment which is a variant on the
embodiment shown in FIG. 14.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
Reference will first be made to FIG. 1, which shows a filling system 1
comprising a tubular filling pipe 2 having at its upper end a pipe mouth
3, which is also of tubular shape and which has a circular opening 4
adapted to receive a closure cap, not shown. The filling pipe 2 has a
lower end which is connected to a fuel tank (not shown).
A first conduit 5 leads upwardly from the fuel tank. The conduit 5 is an
overflow duct which terminates at the level of the upper end of the pipe
mouth 3. A second conduit 6, which is a gas vent duct, also extends from
the fuel tank, up to substantially the same level as the overflow duct. A
third conduit 7, which is a scavenging duct, extends from a scavenging or
depolluting system and terminates at the level of a safety valve 8.
Finally, a fourth conduit 9, namely a fresh air duct, is carried in the
example shown in FIG. 1 by the safety valve 8, though it may be carried by
the pipe mouth 3 instead.
The ducts 5, 6 and 9 and the safety valve 8 associated with the duct 7
provide ventilation for the fuel tank via the pipe 2 and its pipe mouth 3.
As is best seen in FIG. 1, the filling device, constructed as just
described, is formed in two parts, namely a lower part 10 (which will be
referred to as the filling body) and an upper part 11 (which will be
called the filling head). To this end, these two parts 10 and 11 are
permanently joined to each other along a junction plane 12.
In this way, the body 10 of the filling system 1 includes the lower parts
of the overflow duct 5, gas vent duct 6, fresh air duct 9 and filling pipe
2, with these various ducts and the filling pipe being joined to each
other through webs 13, so as to form a monobloc assembly extending up to
the junction plane 12.
The head 11 of the filling system 1 includes the pipe mouth 3 and the upper
parts of the overflow duct 5, gas vent duct 6, fresh air duct 9 and
scavenging duct 7, together with the safety valve 8. These various
elements are made integrally with each other, for example by moulding a
suitable plastics material.
The filling body 10 has a base portion 14 and the filling head 11 has a
base portion 15. These base portions 14 and 15 are mounted in abutting
relationship so as to join the filling head and filling body permanently
together. The base portion 15 has, within its thickness, a passage 15'
which brings the upper and lower parts of the scavenging duct 7 into
communication with each other.
Reference will now be made to FIG. 2, which illustrates a modified form of
the filling system of FIG. 1. In the system shown in FIG. 2, the
scavenging duct 7 is absent. As has already been described in relation to
FIG. 1, the filling system has a filling body 10, which again has the
overflow duct 5, the gas vent duct 6 and a filling pipe 2, these three
components being joined to each other through a web 13 so as to constitute
a monobloc unit.
The filling head 11 includes the safety valve 8, the upper parts of the
overflow duct 5 and gas vent duct 6, and the fresh air duct 9. The filling
body 10 and filling head 11 are again provided with fastening base
portions 14 and 15 for securing the parts 10 and 11 permanently together.
The fuel tank is vented through the filling pipe 2, its pipe mouth 3, the
ducts 5, 6 and 9, and the safety valve 8.
Reference is now made to FIGS. 3 and 4, which show the filling head 11 in
detail, and more particularly that part of it which comprises the safety
valve 8. In FIGS. 3 and 4, the pipe mouth 3 of the filling head 11
comprises a circular wall 16 having open ends 17 and 18 and defining a
hollow, open ended cylinder. In abutment on the end 17 of this cylinder is
a fastening base 19, on to which the filler cap (not shown), for closing
the space 4 in the fastening base 19, can be secured. The open end 18 of
the hollow cylinder of the pipe mouth 3 includes the base portion 15
described above. The passage 15' in the base portion 15 is also seen in
FIGS. 3 and 4. Abutting on the open end 18 is the filling body 10 of the
filling system, so that there is a continuous passage through the two
components thus joined together and between the lower parts of the ducts
5, 6 and 7 and their upper parts.
The safety valve 8 extends upwards from the wall 16, with its axis YY'
making an angle other than zero with the general axis XX' of the filling
head 11. The safety valve a comprises a cylindrical neck portion 20 which
is open at its lower end into the hollow space within the cylindrical wall
16 of the pipe mouth 3. At the upper end of the neck portion 20 is an
opening 21.
The upper part of the scavenging duct 7 is formed integrally along the
interior of the wall 16, and extends along the outer wall 22 of the neck
portion 20 to terminate in an open end 23, at the same level as the
opening 21 of the neck portion 20. The other end of the upper part of the
duct 7 extends towards the base portion 15 to communicate with its lower
portion.
As has already been described in European published patent specification
No. EP 0 336 788A and the corresponding French published patent
specification No. FR 2 628 368A, an obturating or valve member 24 is
arranged within the neck portion 20, to lie on end stop elements 25 which
are arranged close to the intersection between the neck portion 20 and the
cylindrical wall 16 of the pipe mouth 3, in such a way as to prevent any
possible fall of the obturating member 24 into the hollow interior of the
filling head 11.
The obturating member 24 has a float 26 and a valve surface 27 which is
arranged for closing an orifice 28 which is formed in a seating member 29.
In a variant within the scope of the invention, the obturating member 24
may be controlled only by a suitable biassing means, for example a ball
mounted on ramps or a calibrated spring.
The seating member 29 is arranged concentrically with the neck portion 20,
and overlies the opening 21 of the latter and the open end 23 of the
scavenging duct 7. Within the body of the seating member 29, the orifice
28 is arranged so as to be concentric with the float 26. The seating
member also has a second orifice 30, concentric with the orifice 28,
together with an escape passage 31, which brings the orifice 26 or the
orifice 30 into communication with the scavenging duct 7 through the open
end 23 of the latter. From the face 32 of the seating member 29 opposite
to the face of the latter that overlies the openings 21 and 23, an
auxiliary valve 33 is fitted. The auxiliary valve 33 comprises a valve
member 33' which can be calibrated so as to be responsive to over-pressure
or under-pressure by means of a spring 34. The details of this element 33'
can be similar to the embodiment shown in FIGS. 12 and 13 in which we have
elements 72, 73 responsive to both over-pressure and under-pressure. The
valve 33 is trapped between the upper face 32 of the seating member 29 and
the base 35 of a cap 36, which surrounds and overlies the seating member
29 and part of the neck portion 20. The cap 36 is joined to the seating
member 29 and neck portion 26 sealingly and in a non-removable manner. The
cap 36 has a fresh air duct extending from its periphery. In this example,
the fresh air duct is the duct 9, which brings the space defined by the
base 35 of the cap 36, and the upper face 32 of the seating member 29,
into communication with the atmosphere.
The fuel tank venting system shown in FIGS. 3 and 4 operates as follows.
With a fuel cap secured over the opening 4, if any fuel rises up into the
interior of the pipe mouth 3, then this liquid comes into contact with the
float 26 so that the obturating or valve member 24 moves upward in a
straight line along the axis YY' of the safety valve 8 so as to close off
the orifice 28, thus preventing any liquid from entering the scavenging
duct 7.
In the event of an under-pressure or over-pressure arising within the fuel
tank, air is admitted to the tank, or released from it, via the duct 7,
the passage 31 and the orifice 28 of the safety valve 8. In the same way,
vapour build-up in the fuel tank is prevented by release of volatile gases
or vapour from the fuel by the same route.
In the event of the scavenging duct 7 being blocked by some impurity, with
an over-pressure or under-pressure existing within the pipe mouth 3, the
float 26 is in engagement on the end stop elements 25, so that the orifice
28 is open. The pressure cannot be corrected by evacuation of air or
admission of fresh air from the outside through the duct 7, while also
fuel vapour cannot be evacuated via the duct 7. For this reason, the
pressure within the fuel tank will become elevated, and these effects can
cause serious damage to the fuel tank.
Under these circumstances, the valve member 33' of the auxiliary valve 33
opens, thus opening the orifice 30. Fresh air from the outside can then
flow through the fresh air duct 9, the orifice 30 and the orifice 26, so
as to bring the interior of the pipe mouth 3 into communication with the
atmosphere. In this way the excess pressure in the fuel tank is removed,
or the deficiency in pressure is corrected as the case may be, and any
vapour in the tank is allowed to escape.
Reference is now made to FIGS. 5 and 6. In these Figures, the same
essential elements are present as those in FIGS. 3 and 4, and are
indicated by the same reference numerals. As has already been described,
the pipe mouth 3 includes the safety valve 8 having its neck portion 20
with an open end 21, together with a scavenging duct 7 running along the
pipe mouth 3 and neck portion 20 to terminate in an open end 23. The valve
member 24 is again arranged inside the neck portion 20, to bear on the end
stop elements 25, with the valve member 24 having the float 26 and valve
surface 27 for cooperation with the orifice 28 of the seating member 29,
together with the escape passage 31 connecting the orifice 28 with the
open end 23 of the scavenging duct 7.
However, in the arrangement shown in FIGS. 5 and 6, a supplementary duct 37
is formed integrally in the wall 16. The duct 37 has a first portion
extending along the wall 16, and a second portion extending along the
outer wall 22 of the neck portion 20, to terminate in an open end 38 at
the same level as the opening 21 of the neck portion 20. The duct 37 is
arranged symmetrically with the scavenging duct 7, with reference to the
axis YY' of the safety valve 8.
The other end 39 of the supplementary duct 37 is open into an auxiliary
valve 33, which has a valve member 33' that operates, as before, in the
event of an over-pressure or under-pressure. The auxiliary valve 33 has a
housing 40 which is substantially cylindrical in shape and which is also
formed integrally with the wall 16. One end of the housing 14 is in
communication with the open end 37 of the supplementary duct 37, and its
other end 41 lies in the same plane as the open end 17 of the pipe mouth
3. The fastening base 19, already described with reference to FIG. 3,
overlies the open end 17 and the open end 41 of the pipe mouth 3 and
auxiliary valve housing 40 respectively. However, in this example the
fastening base 19 carries the fresh air duct, which here comprises a fresh
air duct 9 that is open into a communication passage 42, which brings the
fresh air duct 9 into communication with the auxiliary valve 33.
A cap 36 is again mounted securely and sealingly over the open end 21 of
the neck portion 20 of the safety valve 8. In this case the orifice 28 is
formed in the body of the cap 36, with the latter also serving as the
seating element 29 for the valve member 24. The orifice 28 is in
communication with the scavenging duct 7 through the escape passage 31,
and with the supplementary duct 37 through an additional communication
passage 43.
The operation of this auxiliary valve and safety valve is substantially
identical with that already described with reference to FIGS. 3 and 4.
Thus the valve member 24 closes the orifice 28 in the event of a surge of
fuel into the interior of the pipe mouth 3, while also depolluting or
devaporising the fuel tank by scavenging excess gas from the latter and
correcting any over-pressure or under-pressure in the tank via the
scavenging duct 7.
However, in the embodiment shown in FIGS. 5 and 6, if the scavenging duct 7
is obstructed by some impurity, the admission or release of air from or to
the outside atmosphere, in order to correct the pressure in the fuel tank
and to scavenge vapour from the latter, takes place through the fresh air
duct 9, the valve 33, the supplementary duct 37, the communication passage
43, the orifice 28 and the interior of the pipe mouth 3.
Reference will now be made to FIGS. 7 and 8, which again include the same
essential elements as those in the embodiments already described, and
which again accordingly carry the same reference numerals. In this third
embodiment, the pipe mouth 3 has the neck portion 20 as already described,
and the valve member 24 is again present with its float 26 and valve
surface 27, and with the upper part of the scavenging duct 7 running along
the wall 16 of the pipe mouth 3 and along the wall 22 of the neck portion
20, to terminate in an open end 23.
However, in this embodiment, the seating member 29 of the safety valve 8 is
in the form of a cap 44 which is secured sealingly over the opening 21 and
the open end 23 of the duct 7. The cap 44 has in its base an orifice 45
which is blind at one end and which is concentric with the valve member
24. The orifice 45 communicates close to its blind end with a passage 46,
which connects the open end 23 of the scavenging duct 7 with the orifice
45. The other end of the orifice 45 is open towards the valve member 24.
The auxiliary valve 33 includes a valve member 33', which is again made
responsive to over-pressure and under-pressure, and which is mounted in a
housing 47, generally cylindrical in shape and having at one of its ends a
communication passage 48 leading into the interior of the pipe mouth 3. At
its other end, the housing 47 has an opening 41 which is arranged as
already described with reference to FIG. 5, in communication with the
fresh air duct 9 through a communication passage 42.
The arrangement shown in FIGS. 7 and 8 operates as follows. In the event of
over-pressure or under-pressure occurring in the fuel tank, or in the
event of any possible surges of fuel towards the space 4 in the fastening
base 19, the valve member 24 operates in the same way as has already been
described.
In the event of the valve member 24, and more particularly its valve
surface 27, becoming seated against the orifice 45, so as to close the
latter and thus prevent any possible communication between the scavenging
duct 7 and the interior of the valve mouth 3: or in the event of the
scavenging duct 7 becoming blocked, then the excess pressure or
under-pressure, and/or the gas vapours in the tank, as the case may be,
can be evacuated through the auxiliary valve 33, via the communication
passage or orifice 48 which brings the fresh air duct 9 into communication
with the interior of the valve mouth 3 through the auxiliary valve 33.
Reference will now be made to FIGS. 9 and 10, which show a further
embodiment, in which the neck portion 20 again carries a valve member 24
having the float 26 and valve surface 27. The scavenging duct 7 again runs
along the wall 16 of the valve mouth 3 and along the wall 22 of the neck
portion 20, to terminate in its open end 23.
However, in the arrangement shown in FIGS. 9 and 10, the seating member 29
of the safety valve 8 itself carries the orifice 28, and is mounted
movably over the opening 21 and the open end 23 of the duct 7. The seating
member 29 is seated over the opening 21 and open end 23 by means of a
spring 49, which bears on the periphery of the seating member and on the
base 35 of the cap 36, so as to surround the seating member. The latter is
therefore sealingly held against the end of the wall 22 of the neck
portion 20 and the wall of the scavenging duct 7. The cap 7 carries the
fresh air duct 9 between the seating member 29 and the base 35.
As shown in FIGS. 9 and 10, the neck portion 20 is coaxially surrounded by,
and spaced away from, a second neck portion 20', which (like the neck
portion 20) projects from the wall 16, and which has an opening in the
same plane as the opening 21 of the neck portion 20. The space between the
two neck portions 20 and 20' is connected to the part of the scavenging
duct 7 that runs along the wall 16, and the open upper end of this space,
again lying in the plane of the opening 21 of the neck portion 20,
constitutes the upper open end of the upper part of the scavenging duct 7.
Thus the cap 7 has a circular shape surrounding the safety valve 8 and
sealingly secured on to the wall of the outer neck portion 20'.
The seating member 29 has a first orifice 28 which is concentric with the
valve member 24. This first orifice 28 is continued in a chamber 50 which
contains an under-pressure valve 51. The valve 51 has a valve member 51'
which cooperates with an orifice 52 for bringing the chamber 50 into
communication with the outside atmosphere through the fresh air duct 9.
In addition, the seating member 29 has a communication passage 31 which
brings the chamber 50 and the outer end of the scavenging duct 7 into
communication with each other.
In this embodiment the outer end 23 is annular. The seating member 29
associated with the under-pressure valve 51 here constitutes the auxiliary
valve 33, responsive to under-pressure or over-pressure.
The operation of this embodiment will be described only with respect to the
case where the scavenging duct 7 is obstructed and/or the valve member 24
is seated against the orifice 28 so as to close the latter.
In the event of over-pressure occurring in the fuel tank, the pressure
within the inner neck portion 20 will be such that it exerts a thrust on
the seating member 29, thus raising the latter upwardly against the spring
49 (see FIG. 10). This causes air to flow towards the fresh air duct, as
indicated in FIG. 10 by the arrow F, and towards the scavenging duct 7 if
the latter is not obstructed.
By contrast, if the scavenging duct is obstructed, with the valve member 24
engaged on the end stop elements 25, the orifice 28 then being open, and
if at the same time the pressure in the fuel tank is reduced, then the
under-pressure valve 51 will be actuated so as to admit air from outside
into the interior of the pipe mouth 3 via the fresh air duct 9, the
orifice 52, the chamber 50 and the orifice 28.
The embodiment shown in FIG. 11 is a combination of those shown in FIGS. 5
and 6 and FIGS. 9 and 10. In the arrangement shown in FIG. 11, the pipe
mouth 3 carries the safety valve 8, the end of the scavenging duct 7, the
supplementary duct 37 (as already described), the auxiliary valve 33, and
the fresh air duct 9 as in FIGS. 5 and 6.
The seating member 29 of the safety valve 2 has an orifice 28 which is
blind at one end. The seating member 29 lies sealingly over the opening 21
and the open ends 33 and 38 of the scavenging duct 7 and supplementary
duct 37 respectively. The seating member 29 is held in engagement by means
of a spring 49, which bears on the periphery of the seating member 29 and
on the base 35 of the cap 36 which envelops the end of the inner neck
portion 20 and the two ducts 37 and 7. In the same way as has already been
mentioned, in a variant the neck portion 20 can of course be surrounded by
a further neck portion 20', so as to define between them a circular space
which is connected to the ducts 7 and 37 running along the wall 16. The
seating member 29 has only a single orifice 26, which is brought into
communication with the scavenging duct 7 through a passage 31, and with
the supplementary duct 37 through a passage 43.
In operation, in the event of an under-pressure or over-pressure occurring
in the fuel tank, and if the scavenging duct 7 is blocked, air will be
admitted or evacuated by flowing through the fresh air duct 9, the
communication passage 42, the valve 33, the open end 39 of the duct 37,
the duct 37 itself, the communication passage 43, and the orifice 28. In
addition, if the valve surface 27 remains seated on the orifice 28 so as
to close the latter, any over-pressure that may occur in the fuel tank
will cause the seating member 29 to rise, so that the excess pressure is
evacuated via the supplementary duct 37 to the auxiliary valve 33. In this
particular embodiment, the main function of the auxiliary valve 33 is
assumed by the seating member 29, which acts as the over-pressure release
valve.
Referring now to FIGS. 12 and 13, the neck portion 20 here has a head wall
53 defining its opening 21 and carrying the orifice 28, the latter being
again concentric with the valve member 24. Beyond this head wall 53, and
integral with the latter, there extends upwardly a generally cylindrical
housing 59, disposed at right angles to the axis YY' of the safety valve
8. This is the housing for the auxiliary valve 33 in this example, and it
has a base wall 60 and an open end 61.
Within the valve housing 59, there is mounted a first hollow member 62,
which is U-shaped in cross section and which has a shape complementary to
the internal shape of the housing 59. The member 62 has a base 63 which is
spaced away from the base wall 60 of the housing by means of projections
64 (FIG. 13). The base 63 extends towards the open end 61 of the housing
in a side wall 65, which is spaced radially away from the side wall of the
housing 59, so as to define between them a free passage 66. The passage 66
is determined by the free space between the base wall 60, the base 63 and
the free space between the side walls of the hollow member 62 and the
housing 59. The passage 66 is sealingly closed towards the open end 61 by
means of an external radial collar 67, which projects from the side wall
65 and engages on the inner surface of the side wall of the housing 59 and
against a sealing ring 68.
The passage 66 is in communication firstly with the scavenging duct 7,
through an orifice provided in the base wall 60 of the housing 59, and
secondly with the interior of the neck portion 20 through the orifice 28.
A second hollow member 69 is carried coaxially within, and forms
effectively an extension of, the first hollow member 62. The second hollow
member 69 bears on the collar 67 of the hollow member 62 through its end
portion 70. The end portion 70 is in the form of an inverted "S" in
longitudinal cross section. A free space 71 is thus defined between the
tease of the hollow member 62 and the end portion 70 of the hollow member
69.
In the hollow of the "S", the second hollow member 69 carries an
over-pressure valve 72 and an under-pressure valve 73. The end portion 70
of the hollow member 69 is extended towards the open end 61 of the housing
by a side wall 74 which is spaced radially away from the side wall of the
housing 59, so as to define between them a free passage 75. The passage 75
is delimited firstly by these two side walls and secondly by the collar of
the first hollow member 62 and a further collar 76. The collar 76 is
carried by the side wall 74 of the second hollow member 69. The passage 75
is sealed by the collar 76 and a sealing ring.
The passage 75 communicates firstly with the interior of the neck portion
20, through an orifice 77 which is formed in the head wall 59 of the neck
portion 20 in line with the passage 75, and secondly with the space 71
between the two hollow members 62 and 70, via an orifice 78 formed in the
side wall 74 of the hollow member 69.
Finally, a third hollow member 79, which acts as an end closure member for
the open end 61 of the housing 59, is arranged coaxially with the other
two hollow members 62 and 69, so as to close the housing sealingly. As
shown in FIG. 13, in this embodiment the fresh air duct 9 is carried by
this third hollow member 79.
The operation of this embodiment of the venting system for the fuel tank is
as follows. Under normal conditions, fuel vapour is removed, and
over-pressure or under-pressure within the fuel tank are corrected,
through the safety valve 8 and the scavenging duct 7. The appropriate flow
of air and/or vapour takes place through the orifice 28, the passage 66
and the scavenging duct 7.
In the event of the valve surface 27 being seated against its seating, so
as to close the orifice 28, any fuel vapour will be removed, and
over-pressures occurring in the fuel tank will be corrected, by flow, this
time, through the orifice 77, the passage 75, the orifice 78, the space
71, the over-pressure and under-pressure valves 72 and 73, and the fresh
air duct 9.
If the scavenging duct 7 is blocked, fuel vapours will be removed, and/or
over-pressures and under-pressures corrected, in the fuel tank, in exactly
the same way.
It will be understood that all the different embodiments of the safety
valve and auxiliary valve described herein may of course be used even when
a scavenging duct is not provided in the filling system, for example as
has been described above with reference to FIG. 2. This will now be
explained in greater detail with reference to the variants shown in FIGS.
14 to 17.
In FIGS. 14 and 15, a pipe mouth 3 is shown which includes a cylindrical
wall 16. A valve member 24 is contained in the neck portion 20 and is
provided with a float 26 and a valve surface 27, all as previously
described with reference to FIG. 3.
A movable valve seating 29 is carried on the top of the neck portion 20, so
as to overlie the opening 21 within the latter. The seating 29 has an
orifice 28 which is concentric with the valve member 014, and is held in
place over the opening 21 by a spring 49, which bears firstly on the
periphery of the seating 29 and secondly on the base 35 of the cap 36,
which carries a fresh air duct 9 between the base of the cap 36 and the
seating 29. The cap 36 is sealingly fixed on the neck portion 20, and has
an inner periphery which is spaced from the circumferential edge of the
seating 29. In the same way as has already been described, the valve
member 24 has the main function of preventing fuel, surging from the fuel
tank, from passing through the orifice 28 and the duct 9, while at the
same time allowing correction of over-pressures or under-pressures in the
fuel tank to be achieved by appropriate flow through the orifice 28 and
the fresh air supply duct 9, while also permitting the evacuation of any
fuel vapours from the system.
As can be seen in FIG. 15, when the valve member 24 lies seated on the
seating 29 so as to close the orifice 28, any over-pressure that may occur
in the fuel tank can be evacuated through the fresh air supply duct 9. To
this end, the pressure subsisting inside the neck portion 20 must be
sufficient to exert a force against the action of the spring 49, in such a
way as to raise the seating 29 and thus free the opening 21, so that the
air or fuel vapours can pass between the inner periphery of the cap 36 and
the side edge of the seating 29, thence being evacuated through the fresh
air supply duct 9. The auxiliary valve 33 is therefore defined, in this
example, by the seating 29 and the associated spring 49.
Reference will now be made to FIGS. 16 and 17, which show a further
modified embodiment of the filling system. In FIGS. 16 and 17, the
cylindrical neck portion 20 has a head wall 53 in which is formed a
coaxial orifice 54, which connects the interior of the neck portion 20
directly with the fresh air duct 9, which is made integral with the head
wall 53. A valve member 24, mounted inside the neck portion 20, has a
valve surface 27 for closing the orifice 54.
The valve member 24 is formed with a coaxial internal spigot having a bore
55, which extends on either side of the level of the valve surface 27 and
continues below the latter. The valve member 24 also has two radial ports
56 which connect the bore 55 with the interior of the neck portion 20.
Mounted within the bore 55, generally above the level of the valve surface
27, is an auxiliary valve 57. The valve member 24 has an orifice 58 which
terminates the bore 55 at the upper end of the valve member, so as to
bring the fresh air duct 9 into communication with the bore 55. The
auxiliary valve 57 is calibrated so as to be responsive to over-pressure
and/or under-pressure, and is arranged to control the opening and closing
of the orifice 58.
In normal operation, an excess or deficiency in the pressure within the
fuel tank is relieved, and fuel vapours are evacuated into the fresh air
duct 9 via the bore 55, the ports 56 and the orifice 54. However, in the
situation which has already been described, in which the valve surface 27
lies against its seating defined by the head wall 53 (so closing the
orifice 54), any excess or deficiency of pressure in the fuel tank can be
corrected by action of the auxiliary valve 57, which thus enables the
interior of the fuel tank to be brought into communication with the fresh
air duct 9 via the orifice 58 and the bore 55, as is shown in FIG. 17.
The present invention is not limited to the various embodiments described
above, which are given only as preferred examples; the invention does
embrace within its scope any other variant within the competence of the
person skilled in the art.
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